The economic growth in much of Asia has been quite remarkable in the last few decades. Unfortunately, along with growth comes intense pollution and atmospheric degradation. Pollutants from the region are being carried upward into the stratosphere during the monsoon season. Findings from a new study conducted by scientists at the National Center for Atmospheric Research (NCAR) provide evidence of the global nature of this atmospheric phenomenon.

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The study was published Thursday, March 25, 2010 in Science Express (link at bottom), and was funded by the National Science Foundation with help from NASA and the Canadian Space Agency.

Satellite observations and data modeling were used to determine the circulation properties associated with the Asian monsoon season. "The monsoon is one of the most powerful atmospheric circulation systems on the planet, and it happens to form right over a heavily polluted region," says the lead author of the study, NCAR scientist William Randel. During the monsoon, air is transported upward into the stratosphere, about 20-25 miles above sea level. This rapid movement of air provides a pathway for pollutants such as black carbon, sulfur dioxide (SO2), nitrogen oxides (NOx), and many others. Once at that level, the pollutants can circulate the globe for several years before returning to lower levels or breaking apart.

It is difficult to predict the future of this global pollutant transport system. Increased industrial activity in Asia would increase the stratospheric damage. Also climate change has the potential to alter the monsoon season. However, whether it would increase or decrease the upward flow of air remains uncertain.

The effects of industrial pollutants in the stratosphere warrants further research. Sulfur-dioxide is known to affect the ozone layer by converting into compounds known as aerosols. Other chemicals may affect global climate by altering the amount of solar heat that reaches the planet surface.